Twenty years ago, 25-30 percent of young people reported that they had tried anal sex. Today, a recent survey shows that 40-45 percent have tried it. Anal sex is more popular among Americans than ever before, but there are almost no medical studies on its effects. Indiana University sex educator Debby Herbenick has just written a fascinating article for Alternet about one of the very few studies ever conducted on it. The study focused on whether women experience pain during anal sex, and how that affects their behavior.

The Zagreb team [who conducted the study] found that about half of women (49 percent) stopped their first experience of anal intercourse because it was too painful to continue – not surprising considering 52 percent of women report not even using lubricant when they first had anal sex! An additional 17 percent of women also experienced pain or discomfort during their first anal sex, but didn't stop their partner. Only about one-quarter of women said their first experience with anal sex was pleasant.

That said, nearly two-thirds tried anal sex again (hopefully this time with lubricant), continuing on another occasion. Those women who found it positive, pleasurable and pain-free were more likely to try it again. About 9 percent of women who had anal sex at least twice in the past year said that they experienced pain every single time. Based on what I know about women who experience pain during vaginal intercourse, my guess is that chronic pain during anal sex is even more common – perhaps hovering in the 10-15 percent range – once the women who actively avoid it because it always hurts are taken into account.

This 9 percent figure is important. It tells us that a similar proportion of women experience pain consistently during anal sex as experience pain consistently during vaginal penetration. That's right: Somewhere around 10 percent of women experience pain during vaginal intercourse or even during daily activities like sitting down or riding in the car. The 9 percent number is also close to the 10-14 percent range that's been identified as the proportion of men who have sex with men who experience pain during anal sex. And though the Zagreb study asked women what sense they made of their pain (most blamed themselves or their sexual practices, suggesting their pain was linked to not feeling fully relaxed, inadequate anal foreplay, or not using sufficient lubricant), the fact is that we still don't know clinically what's causing their pain.

Why don't we study women's responses to sex more often? Obviously there are a lot of taboos in play, but none of those taboos are stopping us from having sex. So why should those taboos stop scientists and doctors from studying it?

Read the rest of the article on Alternet. Read the study that inspired the article here.